The white screen in called preview screen which
android displays based on your theme until drawables and other resources are ready to be loaded in your activity.
first apply custom theme style to your intial activity(Activity which starts first)
like this
android:theme="@style/Theme.MyAppTheme"
and custom style is
<style name="Theme" parent="android:style/Theme" />
<style name="Theme.MyAppTheme" parent="Theme">
<item name="android:windowNoTitle">true</item>
<item name="android:windowContentOverlay">@null</item>
<item name="android:windowBackground">"COLOR YOU WANT TO PLACE WITH WHITE SCREEN"</item>
</style>